Ion exchange removal of calcium carbonate and gypsum from mineral material prior to determination of cation exchange capacity using89Sr++

Abstract

The aim of the present work was to show that ion exchange resins can be used to remove sparingly and slightly soluble salts from calcareous and gypseous soils, which may otherwise cause serious errors in the determination of cation exchange capacity. It was shown that CaCO3 and CaSO4-2H2O can be removed from a mixture with montmorillonite(Ca++) by a mixed bed resin. After resin treatment of the mixture its C.E.C. as retained Sr++ corresponds approximately to the C.E.C. for pure montmorillonite within certain limits. Use of an anion exchange resin alone for removing these salts, however, gave an Sr++ retention well below the C.E.C. for the mineral. It was assumed that this results from the blocking of exchange sites by resin particles.